The microbial community at the top oxidizes the sulfide to corrosive H2SO4[39]. Consistent with

this observation, analysis of 16S rRNA gene clone libraries showed that the community structures differ, with a dominant presence in the BP of sulfate reducing bacteria (SRB) affiliated to Deltaproteobacteria. Specifically, there were 24 phylotypes represented by the genera #www.selleckchem.com/products/MG132.html randurls[1|1|,|CHEM1|]# Desulfobacter Desulfobacterium Desulfobulbus Desulfomicrobium Desulforegula and Desulfovibrio (Additional file 1, Figure S 5). The predominant SRB phylotype (5.4%) in the clone libraries is closely related to Desulfobacter postgatei, a strict anaerobic chemoorganotroph that completely oxidizes acetate to CO2 and reduces sulfur compounds (e.g. sulfate, sulfite, or

thiosulfate) to H2S [40]. In the TP sample, most SOB phylotypes (i.e., 39 of 45) are affiliated to the genus Thiobacillus (Betaproteobacteria) ( Additional file 1, Figure S6), further supporting the importance of this group in concrete corrosion [41]. During the concrete corrosion process it has been shown that Thiobacillus thioparus T. novellus T. neapolitanus, and T. intermedius are involved in the initial and intermediate stages of colonization, while T. thiooxidans dominate in the final stage when the pH reaches values <3 [3]. In our study the majority of the Thiobacillus-like sequences were closely related to uncultured sulfur-oxidizing bacteria clones. Interestingly, two of the dominant clones in our libraries were identified as neutrophilic T. thioparus and T. plumbophilus (>98.5% sequence VX-770 price identity) (Additional file 1, Figure S 6). T. thioparus oxidizes sulfur and thiosulfate, reducing the medium between pH 3.5 and 5 [3]. T. plumbophilus grows by oxidation of H2S and H2 at pH 4 and 6.5 [42]. There were also sequences with a high sequence

homology (>99%) to representatives of the Thiomonas intermedia and Acidiphilium acidophilum, members of the Beta- and Alphaproteobacteria class, respectively. T. intermedia is an obligate aerobe and facultative chemolithoautotroph that produces sulfuric acid at an optimum pH between 5 and 7 [43]. Thiomonas species are Y-27632 2HCl unable to denitrify or oxidize ferrous iron. In contrast, A. acidophilum is able to grow autotrophically or mixotrophically using sulfur or reduced inorganic sulfur compounds, as well as heterotrophically using various organic compounds and is capable of reducing iron [44]. Wastewater concrete corrosion involves the interaction of multiple groups and the establishment of these groups are driven by factors, such as the pH of the concrete, and the temporal dynamics of sulfur compounds [41]. The data from different studies conducted thus far suggest that the composition of species involved in concrete corrosion may vary within different wastewater systems. For instance, our study did not find any hyper-acidophilic SOB sequences (e.g. T.